Circuit-breaker.



S. H.-KEEFER.

--CIRCUI T BREAKER.

APPLICATION HLED DEC-24. 190

Patented Jan. 11, 1916.

"UNITED STATES tum OFFICE.

SAMUEL H. KEEFER, 'OI PLAINFIELZD, NEW JERSEY, ASS IGNQR TO NILES-BEMENT- POND COMPANY, OF JERSEY CITY, NEW JERSEY, A. CORPORATION OF NEW JERSEY.

CIRCUIT-BREAKER.

Specification of Letters Patent.

Patented J an. 11, 1916.

Application filed December 24, 1909. l Serial No. 534,809.

' To all whom it may concern Be it known that I, SAMUEL H. KEEFER, a citizen of the United States, residing in Plainfield, New Jersey, have invented certain Improvements in-Circuit-Breakers, of which the following is a specification.

. As is understood by those skilled in the art, a device designed to break an electric circuit should usually be of such construction and design as to open such circuit when the current flowing therein remains above a predetermined maximum for more than a predetermined time, though it should not elapse after its electromagnet is dene'rgized and before it operates to open the circuit to be protected.

Another object of the invention is the provision of a durable, inexpensive and reliable apparatus, which, while being capable of breaking a circuit if the current therein exceeds a predetermined amount for more than a predetermined time, shall notbreak the circuit when the increase of the current above the permissible maximum is of relas5 tively short duration.

Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and arrangement of-parts'which will be exemplified in the construction hereinafter set forth, and the scope of the application of which will be indicated in the following claims.

In the drawings, in-which is illustrated one of various possible embodiments ofthe invention, Figure 1, is a vertical section illustrating the detail construction of a circuit breaker constructed according to my invention; Fig. 2, is a detached perspective illustrating the detail construction of the coactin portions of the core and of the fixed stud forming part of the invention, and Fig.

-3 is a diagrammatic view illustrating a preferred arrangement of-the electrical wiring.

Similar reference characters refer to $1111- ilar-parts throughout the several views of the drawings.

Referring now to Fig. 1, there is shown at 1 a substantlally cylindrical casing of magnetic material having axially placed openings at its two ends, in the first of which s threaded a cylindrical stud or plug 2 proectlng into the casing for a distance which, 1n the present instance, is slightly in excess of its diameter. Mounted Within the casing concentrically with this stud is a magnetiz- 1n coil or winding 3, having a hollow cylindrlcal interior within which a core 1 is longitudinally movable. This core, as well as the stud 2, is of magnetic material and it is electrically connected to the circuit which it is desired the circuit breaker shall control,

by means of a flexible conductor 5, in the present instance attached to its lower end. A bolt 6 is screwed into the upper end of the core and passes loosely through a central opening in the stud 2; there bein mounted upon its upper end a pair of nuts? and 8 between which is confined a flexible 1 metal strip 9 carrying a contact 10. Similarly, the lower'end of the core 1 has electrically connected to it a second flexible metallic strip 11 having a contact 12 which is designed to engage a fixed contact 13 when the core 4 is at the upper end of its stroke. A second fixed contact 14 is mounted in any suitable manner so as to be engaged by the contact 10 when the core 4 is at the lower end of its stroke, and in order that there shall be no danger of short circuiting any ofthe contacts, I mount a plate 15 of insulating material between the two contacts 13 and 14; and the metallic casing 1.

The construction of the co-acting faces of the stud 2 and of the'core l is clearly illustrated in Fig. 2, from which it will be seen that each of them is provided with two oppositely placed segmental recesses, between which are two similarly formed segmental projections; those of the core being indicated at 16 and 17 and those of the stud being illustrated at 18 and 19.

In order to insure the separation of the core from the stud, there is mounted be-' tween them a spring 20, around the bolt 6- and extended into a recess 21 formed within the lower end of said stud 2. It is obvious that by turning the core 4 relatively to the stud 2, the area of the lower end portions thereof engaged by the coacting adjacent area of said end. As a consequence of this construction, when. these parts are so arranged that the maximum area of contact is permitted, a definite and somewhat prolonged time Will elapse after current is cut off from the magnet winding 3, before the core 4 will move away from the stud 2 under the combined action of gravity and oif the spring 20. This time may be dimlnlshed and finally brought to a minimum by turning the core 4 so that less and less of its endsurface engages the lower face of the stud Under operating conditions, the clrcult breaker may be connected in a number of different ways, one of which is illustrated 1n Fig. 3, where a and I) represent the two ends of a portion of the circuit which it is desired shall be broken when more than a predetermined amount of current flows, and this portion of said circuit includes the fixed contact 13 and the movable contact 12 of the circuit breaker. The winding 3 is connected through a switch, consisting of a pair of fixed contacts 22 and 23 and the movable contact 24, with any suitablesource of current supply, such, for example, as current mains o and d, and the movable contact 24 is operatively connected to the core 25 of the solenoid whose, winding 26 is in series with the circuit a, 6, whose current flow is to be controlled. Under normal conditions the movable contact 24 electrically connects the two fixed contacts 22 and 23, so that current from the mains c and d fiows through the winding 3 and thereby maintains the core 4 in an elevated position in which the movable contact 12 engages the contact 13, so that the part of the circuit a, b is thus closed. If an abnormal current should flow in said circuit and should continue flowing for more than a predetermined time in an amount greater than that for which the circuit breaker was set, the core 25 would be drawn up by the winding 26 and the circuit in which the winding 3 was connected would be broken. As a consequence, the said winding would be deenergized and the core 4 would drop under the action of gravity and of the spring 20, separating the contacts 12 and 13 and breaking the circuit a, b. If

the current flowing in this circuit be but momentarily increased above the normal and the core 25 consequently be raised as above noted, the circuit of the magnet 3 would likewise be broken, but owing to the arrangement and construction described, this latter would not immediately drop, but for a predetermined time would adhere to the lower end of said stud. If during this time the current in the circuit a, I) fell below the allowed maximum, the core 25 would at once be permitted to drop and the movable contact 24'would then again connect the fixed contacts 22 and 23, with the result that the winding 3 would again be energized and there would be no further tendency of the core 4 to drop. As above noted, the time for which the core 4 would be maintained in its upper position aiter the winding 3 was deenergized would depend, not only on its own magnetlc characteristics as well as on those of the casing l and of the stud 2, but also upon the adjustment of the upper end of said core 4 rela: tively to the lower end of said stud 2; said time being greatest when the area of contact of the core and stud is a maximum.

While in Fig. 3, the circuit breaker is illustrated as equipped with a single pair of movable and fixed contacts, it may under certain conditions be provided with a second fixed contact 14 and a corresponding movable contact 10, so that when the circuit between the contacts 12 and 13 is opened that in which the contacts 10 and 14 are included is closed.

vAs many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. It is also to be understood that the language used in the followin a circuit, a fixed core and a movable core within said winding and adqted to contact when said winding is energized, and means for varying the area of contact between said cores, all so proportioned that the cores are retarded to an adjustable extent from separation upon a denergization of the winding.

2. Apparatus of the character described, comprising in combination, a circuit, a winding, means responsive to current changes in said circuit adapted to energize or deenergize saidwinding in accordance with said changes, a fixed core and a movable core within said winding adapted when said winding is energized to contact with each other and maintain said circuit closed, means acting in opposition to said winding and tending to separate said cores to open said circuit, said cores having an adjustable contact surface whereby the effect of momentary deenergization of said winding in permitting said second means to separate said cores maybe nullified to an adjustable extent.

=3. Apparatus-of the character described, comprising in combination, a circuit, a winding, a fixed and a movable core therein, said winding when energized acting through said cores to maintain said circuit closed, a relay adapted to deenergize said winding when the current in said circuit becomes abnormal, means tending to separate said cores, said cores contacting when said winding is energized, whereby upon a momentary deenergization of said Winding said means is rendered ineffective to separate said cores to open said circuit, and means for adjusting the area of contact of said cores.

4:. Apparatus of the character described,

' comprising in combination, a winding normally excited, cooperating fixed and movable cores therein adapted to contact when said winding is excited and to close thereby a circuit, means tending to separate said cores to open said circuit, a relay responsive to current changes in said circuit and adaptbe attracted toward said fixed core when said magnetis energized, means constantly tending to separate said cores in opposition to the force exerted by said magnet, means adapted to make and break the'magnet circuit, said cores contacting when said magnet circuit is closed, whereby upon break of said circuit said separating means is rendered ineffective to separate said cores, and means for adjusting the area of contact between said cores.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

SAMUEL H. KEEFER.

Witnesses:

GEO. B. WEAN, C. "W, BEITER.

a momentary. 

